RCE in Nltk
CVE-2026-12252
In nltk/nltk versions 3.9.3 and earlier, five Stanford interface classes (StanfordPOSTagger, StanfordNERTagger, StanfordParser, StanfordDependencyParser, and StanfordNeuralDependencyParser) are vulnerable to untrusted JAR code execution. These classes accept user-controllable JAR paths and execute them via the `java()` function, which invokes `subprocess.Popen()` without integrity verification. This vulnerability is identical to CVE-2026-0848, which was fixed for StanfordSegmenter by adding SHA256 verification. However, the fix was not applied to these additional classes, leaving them susceptible to arbitrary code execution when loading untrusted JAR files.
Vulnerability class: RCE (Remote Code Execution)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.002 (13.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 13th percentile — 13.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Nltk
- Nltk Nltk/nltk — versions unspecified
Weakness classification (CWE)
References
- huntr.com/bounties/f5c93982-0cc9-4e2e-bb85-1b6ab29a2efb (Exploit, Third Party Advisory)
Frequently asked questions
- What is CVE-2026-12252?
- CVE-2026-12252 is a high-severity vulnerability in Nltk, classified under Code Injection. CVSS score: 7.8/10. Published 2026-07-04.
- How severe is CVE-2026-12252?
- High severity. CVSS v3 base score is 7.8 out of 10.